Macrophages are important mediators of inflammation. Our data show stanniocalcin-1 (STC1) decreases macrophage response to chemoattractants and migration across an endothelial monolayer. STC1 also diminishes superoxide generation in macrophages, by inducing uncoupling protein-2 (UCP2), and inhibits the NF-B pathway. In cultured endothelial cells, STC1 inhibits cytokine-induced changes in permeability and tight junction protein expression. STC1 transgenic mice, which exhibit elevated serum levels and preferential expression of STC1 in macrophages and endothelium, display less inflammatory macrophages in the glomeruli during anti-glomerular basement membrane (GBM) disease, resulting in kidney protection. Overall hypothesis: STC1 suppresses inflammation through inhibition of macrophage recruitment and function, and cytokine-induced increase in endothelial permeability. In Specific Aim I, we will determine mechanisms of UCP2 upregulation by STC1 and the role of superoxide in STC1-mediated inhibition of NF-B in macrophages. In Specific Aim II, we will determine the effect of STC1 on cytokine-induced changes in expression and assembly of tight junction proteins in cultured primary kidney endothelial cells. In Specific Aim III, in the context of anti-GBM disease, we will examine endothelial permeability of native kidney vessels, as well as kidney inflammation and function, after kidney endothelium-specific or macrophage-specific overexpression or deletion of STC1.